1. Field of the Invention
The present invention relates to a method of processing a silicon substrate so as to form a penetration port in the silicon substrate and a method of manufacturing a substrate for a liquid discharge head that discharges a liquid such as an ink to a material to be recorded such as a recording paper.
2. Description of the Related Art
A method of manufacturing an ink jet recording head which is a typical example of the liquid discharge head is described in the following patent documents.
Japanese Patent Application Laid-open No. 2004-148824 discloses a method of manufacturing an ink jet recording head by etching silicon after having been subjected to a trench processing by laser. In this method, a large amount of inscription of a trench with a laser processing is required. However, there is a problem in that time required for the laser processing is extended along with an increase in amount of inscription by the laser processing, which reduces the manufacturing efficiency.
Japanese Patent Application Laid-open No. 2007-237515 discloses a method of manufacturing a substrate for a liquid discharge head in which the substrate is formed with a non-penetration port by laser light and then is subjected to anisotropic etching. According to this manufacturing method, a processing section with a middle portion expanded in a transverse direction is formed. However, even in this method, the section of the ink supply port is also formed in the expanded shape, and thus there is a limitation in the reduction of the width size of the liquid discharge head.
As described above, in the process for forming the ink supply port, in order to reduce the width size of the ink jet head, there is a demand that the passage width of the ink supply port of the silicon substrate is narrowly formed and the ink supply port is effectively formed.
Moreover, in general, the ink supply port is formed by forming a mask on an opposite surface of the silicon substrate and executing the anisotropic etching from the opposite surface. However, in this process, the etching time for forming the ink supply port is long and the passage width of the opposite surface of the silicon substrate is extended in the transverse direction, which makes it difficult to reduce the ink jet head.
Furthermore, in order to reduce the etching time, as described in Japanese Patent Application Laid-open No. 2007-237515, a method whereby a part of the silicon substrate is removed to shorten the anisotropic etching time is effective. The anisotropic etching amount can be reduced to the extent of the depth that a part of the silicon substrate is eliminated, so it is possible to suppress the extension of the ink supply port in the transverse direction to more effectively achieve the reduction in size of the ink jet head and the reduction of the etching time. However, if the etching rates of the respective plane orientations of the anisotropic etching are not controlled, the width of the ink supply port is widened due to the time of the anisotropic etching, and thus, there is a problem in that the elimination amount of the silicon is large, which lowers the production efficiency.